Allow Fo priests to cut mission tree with no skill reduction

[Galatyn 438]

Can add in a check to not reduce skill if the target tree is the mission tree.

[Ekcin 2,417]

+1 It seems to me that this is the only mission type where priest restrictions hit. There is no paving, digging, or mining Valrei mission. And the traitor rewards are high.

[LionIX 354]

Anyone tested wild growthing it dead? (I think it may break the mission)